Rotor head



Feb. 14,V 1967 J. woLF 3,303,888

ROTOR HEAD Filed March 2l, 1966 ATTR/VEY United States Patent O 3,363,888 R HEAD acob Wolf, 629 W. Moynrnensing Ave., Phiiadeiphia, Pa. 19143 Filed Mar. 21, 1966, der. No. 535,357 6 Claims. (Cl. 17d-166.55)

This invention relates to a rotor head for use in helicopters.

In the conventional helicopter rotor head designs presently available rotor blades are pivoted on horizontal and vertical planes. Each blade during one revolution of the hub to which it is mounted as it approaches its most forward point of rotation lags and climbs then after passing this position dives and leads. The horizontal pivot allows the vertical up and down motion and the vertical pivot allows horizontal lead-lag motion.

lf t-he tip path of the blade were to be viewed from the center of rotation its motion would be that of a cone. This cone then would tbe the result of the coning or up motion of the blade about the horizontal pivot and its lead-lag motion about the vertical pivot. The apex of this cone would occur at the point where the blade was attached to its hub or center of rotation. This blade system is known as a fully articulated system.

The present systems require the use of complicated mechanism to achieve this motion which due to the large forces involved are of heavy construction, require frequent maintenance, long down time and consequent large expense.

The principal object of the present invention is to provide a rotor head that is of rigid construction but which possesses all the advantages of a fully articulated system.

A further object of the present invention is to provide a rotor head which is of simple construction but free from likelihood of expensive maintenance and trouble in use.

A further objectof the present invention is to provide a rotor head that is inexpensive to construct and which is of light weight.

A further object of the present invention is to provide a rotor head that is versatile and may be used on a variety of helicopters of both large and small size.

Other objects and advantageous features of the invention will be apparent from the description and claims.

The nature and characteristic features of the invention will tbe more readily understood from the following description taken in connection with the accompanying drawings forming part thereof in which:

FIGURE l is a side elevational View of a helicopter incorporating the invention;

FIG. 2 is a top fragmentary View, enlarged, showing three rotor heads attached to a hub incorporating the invention therein;

FIG. 3 is a vertical sectional view, taken approximately on the line 3-3 of FIG. 2;

FIG. 4 is a horizontal sectional view, taken approximately on t-he line 4--4 of FIG. 3; and

FIG. 5 is a fragmentary vertical sectional view, taken approximately on the line 5 5 of FIG. 4.

It should, of course, tbe understood that the description and drawings herein are illustrative merely, and that various modifications and changes can be made in the structure disclosed without departing from the spirit of the invention.

Like numerals refer to like parts throughout the several views.

Referring now more particularly to the drawings in which a preferred embodiment of the invention is illustrated, the rotor head of the present invention is shown attached to a rotor hub 11. The rotor head comprises rotor head units as shown in FIGS. 2 and 3 each of 3,3%,333 Patented Feb. 14,- 1967 ice which includes a blade 12 attached by rivets 14 to a mounting plate 15. The blades 12 are of conventional construction and ,common in the industry, being formed of a suitable aluminum alloy metal or other suitable material as desired. The plate 15 is engaged and retained in a U shaped portion 17 of a blade shaft 18. Bolts 19 of well known type used in the aircraft industry are provided extending through portion 17 and plate 15 securely fastening them together.

The shaft 18 at its front end and behind the portion 17 is journaled in a ball bearing 2t) and restrained from movement therein by a shoulder 21 on shaft 18 and seal ring 22 between the bearing 2t) and shoulder 21 on shaft 18.

The bearing Zti is securely fastened in an outboard rotor head plate 24, the bearing 2i) being located at a point which is off center of the center of the plate 24 and at a distance to be determined dependent upon the desired cone motion size for the particular installation.

The plate 24 is of circular shape and fitted with a roller bearing 25 extending around its outermost perimeter edge 26. The roller bearing 25 has its inner race 27 secured to the perimeter edge 26 of the plate 24 in any desired manner, such as lby a press fit. The outer race 28 of the bearing 25 is secured to a radial inwardly extending front wall 30 of an outer rotor head housing 31 of the rotor head 1Q. Suitable uid tight seals 32 are provided fastened on the outside surface 33 of the plate 24 and bearing on a curved inner surface 34 of the wall 3ft preventing fluid leakage past the roller bearing 25.

The outer rotor head housing 31 is of cylindrical shape with a hole 35 in the top thereof fitted with a removable plug 35. The hole 35 is utilized for the introduction of an incompressible fluid into the interior of the housing 31. The housing 31 at the rear thereof is closed by an inner rotor head plate 37 which is fastened to the housing 31 and provides a fluid tight seal therewith by the use of suitable fasteners such as screws 38 engaged in threaded holes 39 in the housing 31. The shaft 18 extends inwardly beyond the outer plate 24 and is provided with a collar 40 which extends along a portion of the shaft which -is within the housing 10, the collar 40 is retained on the shaft 18 by keys 41. The keys 41 are engaged in keyways 18d in the shaft 18 and slots 42a in collar 40 and permit of lengthwise movement of the collar 4t) along the shaft 1S ibut prevent any relative rotational movement around the shaft 1S.

For certain types of installations where it is desired to apply a drag or damping action on the shaft 1S, two vanes 42 are provided engaged in vertical slots 43 in t-he collar 4t) one on each side thereof and urged outwardly by springs 44 bearing on their innermost ends 46. The vanes 42 are of semi-rectangular shape and are provided with orifice holes 45 of different sizes extending through the vanes 42. The size of the holes 45 increases to a maximum at the inner end 46 of the vane 42. The vanes 42 bear against a curved inside surface 47 of the outer housing 31 and are urged thereagainst -by the springs 44.

The shaft 1S at its inner end is journaled in a monoball bearing 50, the shaft 18 having an inner retaining shoulder 51 which bears against the ball 52 of the bearing 5t). The bearing l has an outer race 53 which is secured in plate 37 in any desired manner such as by seal and retaining collar 54. The shaft 18 extending inwardly of plate 37 has an inner end 55 which is provided with a pitch change arm 56 keyed thereto by screws 57 but which arm 56 can be fastened to shaft end 55 in any desired manner. The change arm 56 has a split end 5S which is composed of slot 6) and arms 61. A pitch change link 62 is provided engaged and rotatably retained in slot- 60 between arms 61 by means of a pin 63 which passes through holes 3 64 in arms 61 and through hole 65 in link 62. The link 62 extends down through a hole 66 in a circular plate 7) of hub 11 to a conventional swash plate (not shown) and pitch adjustment and maintenance mechanism of well known type.

The housing 31 is fastened to the plate 70 of the hulb 11 by screws 68. The plate 70 is of circular shape and in the example as illustrated in FIG. 2 can have three rotor heads 1t) attached at spaced locations around the hub 11. The housing 31 may be filled through hole 35 with a suitable incompressible hydraulic uid for the purpose of retarding the motion of vanes 42 and attached mechanism.

The mode of operation will now be pointed out. When it is desired to operate the rotor head 11, the helicopter motor is started and the hub 11 is caused to rotate. The pitch of the blades is set through the pitch change mechanism (not shown) in the operating section of the helicopter then through the pitch change link 62, arm 56 and shaft 18 and plate 15 to blade 12. The pitch change mechanism referred to in the helicopter is of conventional well known type and employs a cam (not shown) so that the pitch setting is maintained throughout the rotation of the hub 11.

Assume at the start of rotation that the shaft 18 and bearing 20 in plate 24 is at its closest distance to the plate 70 of the hub 11 that it can attain. As the hub 11 rotates about its center the forces of rotation will act on each of the blades 12 urging them vertically upwardly and horizontally. The forces will be transmitted from the blade 12 and act on the shaft 18 which is free to rotate in a circular motion with the end plate 24 which will cause the plate 24 to be rotated on its bearings 25 and move shaft 18 and *blade 12 upwardly. As the hub 11 continues its rotation the blade 12 will reach its uppermost point and then due to gravity and the hub 11 angular inclination with respect to a horizontal plane through the edge thereof the dynamic forces will urge the blade 12 down whereupon the plate 24 and shaft 1S will rotate until the shaft is at its lowermost point as at the start of the revolution. It should be noted that the path of the blades 12, as viewed from outside, is a cone with the apex at the center of bearing 50. The vanes 42, if employed, during the revolution of plate 24 and shaft 18 act as a brake with more holes being exposed to Huid resistance as the varies corne out of the slots 43. The pitch of the blades 12 can be varied during any point of this revolution and at any time in the manner as previously described.

I claim:

1. A rotor head for helicopter blades comprising a hub,

an outer cylindrical housing for each of said blades carried by said hub,

said housing having an inner end closure plate ixedly mounted with respect to said housing, and

an outer end closure plate rotatably mounted with respect to said housing,

a blade carrying shaft extending through said housing and lbeyond said end plates,

members at the inner end of said shaft for controlling the angular positioning of said shaft,

a pivotal `bearing member in said inner end closure plate for said shaft, and

bearing members in said outer end closure plate rotatably mounting said shaft.

2. A rotor head, as dened in claim 1 in which said bearing members in said inner end plate include a ball type mounting.

3. A rotor head as defined in claim 1 in which said outer end plate and said housing having a thrust bearing therebetween.

4. A rotor head as defined in Claim 1 in which said shaft has damping members thereon within said housing.

5. A rotor head as dened in claim 1 in which said shaft has a plurality of vanes thereon and movable therewith in said housing, said varies have openings therethrough, and

said housing has a damping liquid thereon for engagement by said vanes.

6. A rotor head as defined in claim 5 in which said openings in said varies are of variable size.

References Cited by the Examiner UNITED STATES PATENTS 2,506,210 5/1950 Goodson et al. 170--160.56 X

EDGAR W. GEOGHEGAN, Primary Examiner.

EVERETTE A. POWELL, JR., Examiner. 

1. A ROTOR HEAD FOR HELICOPTER BLADES COMPRISING A HUB, AN OUTER CYLINDRICAL HOUSING FOR EACH OF SAID BLADES CARRIED BY SAID HUB, SAID HOUSING HAVING AN INNER END CLOSURE PLATE FIXEDLY MOUNTED WITH RESPECT TO SAID HOUSING, AND AN OUTER END CLOSURE PLATE ROTATABLY MOUNTED WITH RESPECT TO SAID HOUSING, A BLADE CARRYING SHAFT EXTENDING THROUGH SAID HOUSING AND BEYOND SAID END PLATES, 